1. Field of the Invention
The present invention relates to an automatic vehicle wiper system.
Priority is claimed on Japanese Patent Application No. 2004-266643, filed Sep. 14, 2004, the content of which is incorporated herein by reference.
2. Description of Related Art
Conventionally, in a vehicle such as an automobile, automatic wiper systems are known that automatically carry out the wiping action of a wiper by using a rain sensor in order to reduce the burden of the vehicle operation on the driver while driving in rain. Rain sensors are known that estimate the amount of rainfall based on the amount of light received when light emitted from a light emitting portion is reflected by the front windshield and made incident on a light receiving portion. The rain sensors are placed in a small field of locations on the front windshield that do not obscure the field of view of the driver (refer to Japanese Unexamined Patent Application, Application No. 2003-109184).
However, the number of raindrops striking the rain sensors is small when the vehicle has stopped in comparison to when the vehicle is traveling. Thus, for example, the rain sensors may determine that the condition is a light rainfall even when the condition is a moderate rainfall, and thereby the wiping action of the wipers is inhibited. When the vehicle starts to move again (accelerate) after having stopped, a predetermined amount of time is necessary in order to estimate an amount of rainfall that corresponds to the actual rainfall conditions. This predetermined amount of time is because of the variance in frequency with which raindrops will strike the rain sensor and the like.
In contrast, a rain sensor may determine that rainfall is heavy even during light rainfall conditions in the case that, for example, the raindrops are concentrated by chance at a location at which rain sensors are provided (even if the rainfall conditions are identical, the variance of frequency of raindrops striking the rain sensor while traveling and while stopped are different). In this case as well, in order to estimate the actual amount of rainfall accurately, a filter may be applied to the sensitivity of the rain sensor.
However, in the structure described above, when the vehicle starts to move again after having stopped, even when the rainfall condition is moderate or greater, the wiping action of the wiper may not be appropriate for the rainfall conditions(for example, the wiper may not carry out the wiping action even though rain is falling), because of the variance in frequency with which the raindrops will strike the rain sensor or because the rain sensor estimates the amount of rainfall through a filter, and thus the driver may experience distress.
Thus, the present invention provides an automatic vehicle wiper system that can carry out a wiping action of the wiper that corresponds to the rainfall conditions even when the vehicle starts to move again after having stopped.